Formation of Highly Stabilized Intramolecular Dimer Radical Cation and π-Complex of [3 n ]Cyclophanes (n = 3, 5, 6) during Pulse Radiolysis

Formation of radical cation and charge-transfer complex of [3 n ]cyclophanes (n = 3, 5, 6) was investigated by transient absorption spectroscopy during pulse radiolysis. Radical cations of [3 n ]cyclophanes showed the charge resonance band around 700 nm which exhibited a blue-shift as the number of trimethylene bridges increased, indicating formation of highly stabilized intramolecular dimer radical cation of [3 n ]cyclophanes. The absorption peak of the charge-transfer complex with chlorine atom also showed the shift in accord with the oxidation potential of [3 n ]cyclophanes.